In this work, we present an approach for tracking the feet of multiple users in CAVE-like systems with under-floor projection. It is based on low-cost consumer cameras, does not require users to wear additional equipment, and can be installed without modifying existing components. If the brightness of the floor projection does not contain too much variation, the feet of several people can be successfully and precisely tracked and assigned to individuals. The tracking data can be used to enable or enhance user interfaces like Walking-in-Place or torso-directed steering, provide audio feedback for footsteps, and improve the immersive experience for multiple users.